System and method for characterizing an upper airway using speech characteristics

ABSTRACT

The present invention relates to systems and methods for characterizing at least one anatomical parameter of an upper airway of a patient by analysing spectral properties of an utterance, comprising: a mechanical coupler comprising means for restricting the jaw position of the patient; means for recording an utterance; and processing means for determining at least one anatomical parameter of the upper airway from the recorded utterance and comparing the recorded utterance to a threshold value. In addition the present invention relates to the use of the above mentioned systems as a diagnostics tool for assessing obstructive sleep apnea.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a system and method for characterizingan upper airway using speech characteristics.

BACKGROUND OF THE INVENTION

Obstructive Sleep Apnoea (OSA) is a disease whereby the upper airway isobstructed many times per night to such an extent that the patient isunable to breathe (apnoea) or has a reduced breathing capacity(hyponea). Diagnosis of OSA can be done in a sleep lab by monitoring apatient during an overnight measurement. If the total of number ofapnoea's and hyponeas exceeds a certain limit, the OSA diagnosis isassigned.

Jung et al disclose that predictive indicators of OSA are the anatomicalfeatures related to the upper airway in Predictive value of Kushidaindex and use acoustic pharyngometry for the evaluation of upper airwayin subjects with or without obstructive sleep apnoea. (J Korean Med Sci,2004. 19(5): p. 662-7). Jung et al also disclose that the spectralcharacteristics of speech, notably vowels, depend on the anatomicaldimensions of the throat. As a result of the latter, spectralcharacteristics of speech can be used as indicators for OSA. For this anacoustic pharyngometer can be used to actively extract geometricparameters of the upper airway by sending an acoustic signal into thethroat and processing the reflections of the latter. However,test/retest validity and the accuracy of an acoustic pharyngometrymeasurement performed by devices known in the art is not that high.

CA2585824 discloses a method for screening OSA, namely to derive flowinformation from breathing sounds in the ear, and combine them with thelevel of snoring. However, the method disclosed in CA '824 can only beused to detect apnoea as they happen.

In addition, unfortunately these diagnosis tools for OSA common in theart are used in a sleep lab, which is expensive, time-consuming anduncomfortable for the patient. Furthermore, the methods at present usedfor screening OSA are very tedious and labour-intensive.

Therefore a need still exists for an improved and less time-consumingtest for daytime investigating and screening of OSA in a short andconvenient way.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a system and methodfor characterizing an upper airway using speech characteristics.

The above objective is accomplished by a method and system according tothe present invention. Particular and preferred aspects of the inventionare set out in the accompanying independent and dependent claims.Features from the dependent claims may be combined with features of theindependent claims and with features of other dependent claims asappropriate and not merely as explicitly set out in the claims.

A first aspect of the invention relates to systems for characterizing atleast one anatomical parameter of an upper airway of a patient byanalyzing spectral properties of an utterance, the system comprising:

-   -   a mechanical coupler comprising means for restricting the jaw        position of the patient;    -   means for recording an utterance; and    -   processing means for determining at least one anatomical        parameter of the upper airway from the recorded utterance and        comparing the recorded utterance to a threshold value.

In some embodiments the characterization can be performed autonomously.The system and method according to the present invention functionsindependently: once the operation is started, it continues until theoperation is terminated, without manual intervention, but possibly underthe control of a controller. Advantageously, the system according toembodiments of the present invention can autonomously check whether thata user has preformed the required utterance.

In some embodiments the processing means provides real-time feedback.Yet in other embodiments the system further comprises means for speechrecognition for controlling correctness of the recorded utterance.

In other embodiments the system further comprises means for deliveringat least one respiratory drug through the upper airway of the patient.

In one embodiment of the present invention the at least one anatomicalparameter is the cross-section of the upper airway and wherein thesystem further comprises means for determining at least one point oftime when the cross-section is maximal during an utterance.

In yet another embodiment the system further comprises means fordelivering at least one respiratory drug through said upper airway ofthe patient at said at least one point of time when said cross-sectionof the upper airway is maximal. In one embodiment of the presentinvention the respiratory drug delivering means comprises a timingmechanism.

A second aspect of the invention relates to the use of the abovementioned systems as a diagnostics tool for assessing obstructive sleepapnea.

A further aspect of the invention relates to methods for assessing atleast one anatomical parameter of an upper airway of a patient byanalyzing spectral properties of an utterance, comprising the steps of:

-   -   restricting a jaw position of the patient;    -   recording an utterance;    -   comparing the recorded utterance with a threshold value; and    -   determining the at least one anatomical parameter of the upper        airway from the recorded utterance and the comparison of the        recorded utterance with a threshold value.

In preferred embodiments the method further comprises the step ofproviding real-time feedback.

In some embodiments the method further comprises the step of adaptingthe patient's body position.

In other embodiments the method further comprises the step of storingthe spectral properties of the recorded utterance in a database.

In yet other embodiments of the invention the threshold value isdetermined by means of speech recognition.

The invention according to embodiments of the invention further includesa method wherein the at least one anatomical parameter is thecross-section of said upper airway and wherein said method furthercomprises the step of determine at least one point of time when thecross-section is maximal when executing an utterance.

Embodiments of the invention include a method further comprising thestep of delivering at least one respiratory drug in the upper airway ofthe patient.

The teachings of the present invention permit the design of improvedmethods and systems for guiding a user in performing accurate andreliable measurements for characterizing an upper airway.

The above and other characteristics, features and advantages of thepresent invention will become apparent from the following detaileddescription, taken in conjunction with the accompanying drawings, whichillustrate, by way of example, the principles of the invention. Thisdescription is given for the sake of example only, without limiting thescope of the invention. The reference figures quoted below refer to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic representation of the approximated articulatorymodel of the vocal tract.

FIG. 1 b is a schematic illustration of the approximated articulatorymodel using a concatenation of four lossless cylindrical acoustic tubes.

FIG. 2 is a schematic representation of the system according to anembodiment of the present invention.

FIG. 3 illustrates a representative output of an acoustic pharyngometrymeasurement.

FIG. 4 a and FIG. 4 b illustrate a real time estimation of upper airwaytract based on uttered sounds using a system according to an embodimentof the present invention.

In the different figures, the same reference signs refer to the same oranalogous elements.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

The present invention will be described with respect to particularembodiments and with reference to certain drawings but the invention isnot limited thereto but only by the claims. Any reference signs in theclaims shall not be construed as limiting the scope. The drawingsdescribed are only schematic and are non-limiting. In the drawings, thesize of some of the elements may be exaggerated and not drawn on scalefor illustrative purposes.

Where the term “comprising” is used in the present description andclaims, it does not exclude other elements or steps. Where an indefiniteor definite article is used when referring to a singular noun e.g. “a”or “an”, “the”, this includes a plural of that noun unless somethingelse is specifically stated.

Furthermore, the terms first, second, third and the like in thedescription and in the claims, are used for distinguishing betweensimilar elements and not necessarily for describing a sequence, eithertemporally, spatially, in ranking or in any other manner. It is to beunderstood that the terms so used are interchangeable under appropriatecircumstances and that the embodiments of the invention described hereinare capable of operation in other sequences than described orillustrated herein.

Moreover, the terms top, bottom, over, under and the like in thedescription and the claims are used for descriptive purposes and notnecessarily for describing relative positions. It is to be understoodthat the terms so used are interchangeable under appropriatecircumstances and that the embodiments of the invention described hereinare capable of operation in other orientations than described orillustrated herein.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention. Thus, appearances of the phrases“in one embodiment” or “in an embodiment” in various places throughoutthis specification are not necessarily all referring to the sameembodiment, but may. Furthermore, the particular features, structures orcharacteristics may be combined in any suitable manner, as would beapparent to one of ordinary skill in the art from this disclosure, inone or more embodiments.

Similarly it should be appreciated that in the description of exemplaryembodiments of the invention, various features of the invention aresometimes grouped together in a single embodiment, figure, ordescription thereof for the purpose of streamlining the disclosure andaiding in the understanding of one or more of the various inventiveaspects. This method of disclosure, however, is not to be interpreted asreflecting an intention that the claimed invention requires morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive aspects lie in less than allfeatures of a single foregoing disclosed embodiment. Thus, the claimsfollowing the detailed description are hereby expressly incorporatedinto this detailed description, with each claim standing on its own as aseparate embodiment of this invention.

Furthermore, while some embodiments described herein include some butnot other features included in other embodiments, combinations offeatures of different embodiments are meant to be within the scope ofthe invention, and form different embodiments, as would be understood bythose in the art. For example, in the following claims, any of theclaimed embodiments can be used in any combination.

Furthermore, some of the embodiments are described herein as a method orcombination of elements of a method that can be implemented by aprocessor of a computer system or by other means of carrying out thefunction. Thus, a processor with the necessary instructions for carryingout such a method or element of a method forms a means for carrying outthe method or element of a method. Furthermore, an element describedherein of an apparatus embodiment is an example of a means for carryingout the function performed by the element for the purpose of carryingout the invention.

In the description provided herein, numerous specific details are setforth. However, it is understood that embodiments of the invention maybe practiced without these specific details. In other instances,well-known methods, structures and techniques have not been shown indetail in order not to obscure an understanding of this description.

The following terms or definitions are provided solely to aid in theunderstanding of the invention.

The term “utterance” used herein relates to a complete unit of speech inspoken language. It is generally but not always bounded by silence. Itcan be represented and delineated in written language in many ways. Itis obvious that utterances do not exist in written language, only theirrepresentations do.

The term “real-time” relates to hardware or software systems that aresubject to a “real-time constraint”, for instance operational deadlinesfrom event to system response. As a result real-time programs preferablyexecute within strict constraints on response time. By contrast anon-real-time system is one for which there is no deadline, even if fastresponse or high performance is desired or preferred. The need ofreal-time software is often addressed in the context of real-timeoperating systems, and synchronous programming languages, which provideframeworks on which to build real-time application software. Real-timecomputations can be said to have failed if they are not completed beforetheir deadline, whereby their deadline is relative to an event. Areal-time deadline must be met, regardless of the system load.

The term “articulator” or “speech organ” relates to organs which canproduce the many sounds or utterances needed for language. Organs usedinclude the lips, teeth, tongue, alveolar ridge, hard palate, velum(soft palate), uvula and glottis. Speech organs or articulators can beof two types: passive articulators and active articulators. Passivearticulators remain static during the articulation of sound, such asupper lips, teeth, alveolar ridge, hard palate, soft palate, uvula, andpharynx wall, whereas active articulators move relative to these passivearticulators to produce various speech sounds, in different manners. Themost important active articulators are the tongue, the lower lip andglottis.

Human beings produce utterances via the interaction of the differentphysiological structures of articulators wherein aerodynamic energy istransformed into acoustic energy. Aerodynamic energy refers to theairflow through the vocal tract. Its potential form is air pressure; itskinetic form is the actual dynamic airflow. The acoustic energy isvariation in the air pressure that can be represented as sound waves.Air cavities are containers of air molecules of specific volumes andmasses. The main air cavities present in the articulatory system are thesupraglottal cavity and the subglottal cavity. They are so-named becausethe glottis, the openable space between the vocal folds internal to thelarynx, separates the two cavities. The supraglottal cavity or theorinasal cavity is divided into an oral subcavity (the cavity from theglottis to the lips excluding the nasal cavity) and a nasal subcavity(the cavity from the velopharyngeal port, which can be closed by raisingthe velum to the nostrils). The subglottal cavity consists of thetrachea and the lungs. The atmosphere external to the articulatory stemmay also be consisted an air cavity whose potential connecting pointswith respect to the body are the nostrils and the lips. When looking atthe properties of vowel sounds one can observe a number of properties ofvowel sounds which tell us a great deal about how they must begenerated. For instance if they have a pitch, they are periodic signalsand different vowels have different timbres, so they must have differentharmonic amplitudes in their spectra. But if the same vowel can bespoken on different pitches, and different vowels can be spoken on thesame pitch, the pitch must be set independently from the vowel qualityand if the same vowel can be spoken on different voice qualities, thevoice quality must be set independently from the vowel quality. Thevowel quality seems to depend mostly on tongue position: front-back andopen-close, but vowel quality can also be affected by the position ofother articulators, the jaw, lips and velum.

All of these above mentioned characteristics of vowels can be analysed,for instance by using models used to describe the production of vowelsounds. One known model which can be used to describe an upper airway ora vocal tract is the approximated articulatory model of the vocal tractillustrated in FIG. 1 a. An elementary segment (1, 2, 3, 4, 5, 6, 7, 8,9 or 10 in FIG. 1 a) of the upper airway is represented by a cylindricaltube of a specific length and cross-section area. When a sound wavetravels through a series of cylindrical tubes comprising differentcross-section areas, the sound wave is partially reflected when crossingfrom one segment to another. FIG. 1 b shows a schematic illustration ofthe approximated articulatory model using a concatenation of fourlossless cylindrical acoustic tubes, each of length and cross-sectionarea A. Thus the upper airway can be viewed as an acoustic tube ofvarying cross-sectional area terminated by the vocal cords on one endand by the lip opening at the other.

Another model which can be used is the source-filter model of soundproduction in the upper airway. This model of sound production assumes asource of sound and a filter that shapes that sound, organised so thatthe source and the filter are independent. This independence allows oneto measure and quantify the source separately from the filter. For vowelsounds, the source of sound is the regular vibration of the vocal foldsin the larynx and the filter is the whole vocal tract tube between thelarynx and the lips. The source-filter model can also be applied tofricative sounds, whereby the source of sound is the turbulencegenerated by passing air through a constriction, and the filter is thevocal tract tube anterior to the constriction.

It is clear from the above that the spectral characteristics of speech,notably vowels, clearly depend on the anatomical dimensions of a throat.All articulators that contribute to the spectral shaping of an utterancecan be described and visualized in real-time for instance by applying amethod disclosed by D. Hill et al in Proceedings of AVIOS '95, the 14thAnnual International Voice Technologies Applications Conference of theAmerican Voice I/O Society, San Jose Sep. 11-14, 1995, AVIOS: San Jose,pp. 27-44. For the present invention preferably the articulators whichinfluence the cross-section of an airway are determined. Morespecifically, the geometry of an upper airway is preferably determinedusing the above mentioned models. Moreover, the present invention canalso be applied using natural inhaled/exhaled breathing noise and notonly utterance, for instance during sleep or prior to drug inhalation.

Because the upper airway is geometrically very complex and variable intime, establishing a standard operating protocol and understanding ofthe possible sources of artefacts is of great importance in obtainingreliable results. Of equal importance is the repeatability ofmeasurements obtained to ensure validity of the results.

The invention according to an embodiment relates to a system 10 forcharacterizing at least one anatomical parameter of an upper airway of apatient, for instance a throat or a vocal tract, by analysing spectralproperties of an utterance The invention provides in one embodiment asystem for characterizing at least one anatomical parameter of an upperairway of a patient by analysing spectral properties of an utterance,the system comprising:

-   -   a mechanical coupler 1 comprising a mouthpiece 11 which        restricts the jaw position and which can be anatomically fitted        according to the utterance the patient is supposed to perform;    -   a sound recording unit 2 for recording an utterance, for        instance a microphone or the mechanical coupler used as a        free-floating microphone; and    -   a computing device preferably comprising a non-transitory memory        adapted to determine at least one anatomical parameter of the        upper airway from the recorded utterance and comparing the        recorded utterance to a threshold value.

The system according to an embodiment of the invention is illustrated inFIG. 2. The system comprises a mechanical coupler 1 which is used totransmit a generated audible sound signal, for instance a vocalutterance or a non-vocal utterance, like for instance naturalinhaled/exhaled breathing noise, from the to be examined cavity into thesystem 10. In embodiments of the present invention both vocal andnon-vocal utterances can be generated, however vocal utterances mayprovide less information on the lower airway system as compared tonon-vocal utterances. In one embodiment of the invention the mechanicalcoupler 1 enables the restriction of the jaw position. The latter is inone embodiment of the invention enabled by using different mouthpieces11 which can be anatomically fitted according to the utterance thepatient is supposed to perform. The mouthpiece 11 can ensure, forexample, that the teeth and jaws are in a certain position and that theopening of the mouth has a very specific diameter leading to welldefined measurement setups. In addition, the mouthpiece 11 can restrictthe position of the tongue as well. Advantageously when the jaw positionis fixed and the teeth and jaws are in a certain position the opening ofthe mouth has a very specific diameter leading that the variability inthe utterances is reduced and thus enhancing the precision of themeasurement.

The mechanical coupler 1 can further comprise a probe 12. The mechanicalcoupler 1 and, in one embodiment of the invention, the probe 12 cancomprise means for recording an utterance, for instance by using a soundrecording unit 2 for recording the utterances. In one embodiment of theinvention the mechanical coupler 1 and the probe 12 can have a tubularshape but different shapes can be applied as well. In some embodiment,the sound recording unit 2 is integrated with the tube formed by thecoupler 1 and the probe 12. This can be enabled for instance byintegrating a snoring microphone in an OptiVent In-Line Spacer bothdeveloped by Philips Respironics. The setup illustrated in FIG. 2 showsa tubular probe 12 whereby the tubular probe 3 itself can be used as afree-floating microphone 2 without a well defined connection to a usergenerating the utterances or inhaled/exhaled breathing noise. Afree-floating microphone is a microphone where its head has no contactwith the damping element or the drum and which is received in a holder.The sound recording unit 2 is in one embodiment of the inventionconnected to a processing means 5. In another embodiment of theinvention the processing means 5 can determine the anatomical parametersof the upper airway from the recorded utterances or inhaled/exhaledbreathing noise and compare the determined anatomical parameters to athreshold value. In addition, the processing means 5 can providefeedback in real-time as a result of processing the obtained data inreal-time. The processing means 5 can be a computing device comprisingin one embodiment of the invention a non-transitory memory. Morespecifically a personal computer, a laptop, a tablet computer, a smartphone, a mobile phone, a watch or any electronic visual displays whichcan comprise a touchscreen can be used. In another embodiment of thepresent invention the processing means 5 can be executed by a singleoperation for instance with respect to a predetermined button, and hencecan be executed by an exceedingly simple operation. All processing means5 which are known to a person skilled in the art can be used, as well asany software which could enable the characterization of the necessaryanatomical parameters can also applied. For instance one canadditionally use an adapted version of the EncorePro 2 software byPhilips which can display patient compliance data stored by the variouselement of the system according to the present invention throughgraphical and statistical analysis. With Encore Pro, a patient'stherapeutic history can be maintained and the patient's therapycompliance can be assessed.

The system according to embodiments of the present invention can furthercomprise means to instruct and control a patient's body position. Theupper airway geometry at different body positions (e.g. lying down andstanding) can be important to obtain good discriminatory factors betweenpatients suffering from OSA and non-OSA patients. The means to instructand control a patient's body position can for instance be enabled byadding a 3D accelerometer to the system as illustrated in FIG. 2, whichgives the orientation of the system and can be used to instruct andcontrol the patient via the user interface (e.g. the patient could beasked to first do a measurement in standing and then in lying position).

In other embodiments, the processing means 5 can also be connected to adatabase 4 (locally or remotely) and for instance a loudspeaker, adisplay or both 6 which can be used as means to provide the feedback toa user. In one embodiment of the invention the display comprises aninterface to instruct and provide feedback to the test subject, wherebythe usability of the interface is very easy to use by the test subject.In yet another embodiment of the invention the user interface comprisesat least one screen, whereby one screen can be a main screen whereasanother screen can be used to select a particular parameter, forinstance a compression. In addition, many of the functionality's thatare important for a good result which can be done autonomously by thedevice are done by the system itself. An example of this is thedetermination of the frame rate which is done by determining the numberof images in the sequence and the length of the speech fragment andcalculating the frame rate using these numbers.

According to some embodiments the database 4 in one embodiment of theinvention contains a predefined sequence of utterances that a user canperform. In some embodiments, the database 4 can contain a set ofsequences, from which an operator can choose.

In other embodiments, the processing means 5 can for instance beintegrated or installed on a mobile device, for instance a mobile phone.In this example, a screen or speaker of the mobile phone can be used asmeans to provide feedback to a user and accordingly an integratedmicrophone which is standard on a mobile phone can be used as a soundrecording unit. In one embodiment of the invention the mechanicalcoupler 1 can be a cover that one can attach to the cell phone wherebysaid cover comprises a tube in front of the microphone. In anotherembodiment of the invention the tube can be used as means to fix themount of a user in a predefined way in relation to the integratedmicrophone. Advantageously, using a mobile phone enables simple andconvenient accurate measurements for daytime screening for obstructivesleep apnoea (OSA). In addition, most mobile devices comprise anaccelerometer, which would easily be adapted to instruct and control apatient's body position.

The invention according to some embodiments can provide real-timefeedback for optimal administration and delivery of respiratory drugs.Knowledge of the upper airway anatomy can improve the proportion of theadministered drugs that have to be delivered to a desired location. Drugdelivery systems known in the art are not efficient since only about 25%of the administered drug is delivered where it should be, by obtainingreal-time feedback on the upper airways one can model the flow of theparticles through these upper airways. Knowledge of the upper airwayanatomy can improve the proportion of the administered drug that shouldbe delivered to the desired location. In respiratory drug delivery theproblem is getting the drug “beyond the throat”. Once beyond the throatthere are various systemic routes for the drug to reach the targetedalveoli. More drugs delivered “beyond the throat” means a shortertreatment time which is a real differentiator. The means for deliveringat least one respiratory drug through the airway of a patient can forinstance be an aerosol device, the I-neb AAD system by PhilipsRespironics which is a fast aerosol generating system can be used. Byapplying the aerosol technique, a uniform distribution of the drugs witha greater extent of penetration into the peripheral or the alveolarregion of the lung can be achieved. The exact dose of the respiratorydrugs can be calculated and visualized by applying a flow modelling andbased on this the particle delivery is modelled for instance by applyingCFD tools like for instance Star CD and Star CCM+ manufactured byCD-adapco. More specifically the particle delivery and the timing of theaerosol generation can be optimized and in this way the drug deliverycan be personalized but restricted by the medication prescription. Insome embodiments of the invention the cross-section of the upper airwayis determined by the processing means 5 and in addition a point in timewhen the cross-section is maximal during an utterance can be determined.This point of time when the cross-section of the upper airway ismaximal, can be used for the timing of the aerosol generation, whichthen can be optimized for drug delivery, thus providing a system tuningapproach. In addition a mechanical coupler restricting the jaw position,for instance by applying a stepped-mouthpiece (K. Nikander et al in“Manipulation of upper airway volume using a stepped mouthpiece” ERS,September 2010) can be used as a way to force the upper airways to openup. Feedback to the patient on the way his/hers upper airway is openedup is beneficial to this goal. In addition it may support adherence andcompliance. Advantageously embodiments of the present invention enablethe amount of drug delivery to be more controllable, consistent andrepeatable over the various therapy sessions.

A method according to an embodiment of the invention can comprise one ofthe following steps: the system tells the patient which utterance toperform, which the system records. In a next step a processing means 5performs can check on the correctness of the recorded utterance, forexample by means of speech recognition to determine whether the correctutterance has been performed. Several speech recognition models known inthe art can be used to enable the latter, for instance by applying avector Taylor series approach for environment-independent recognition,or by using a parallel model combination (PMC) scheme, or hidden Markovmodels. If the utterance was not correct, the system can ask the patientto repeat it. In a next step the system can repeat the previous stepsuntil all predefined utterances have been performed correctly by thepatient. The processing means can then extract and analyse the featuresimportant for OSA diagnosis. An example of a method which can be used isdisclosed by Robb et al in Vocal tract resonance characteristics ofadults with obstructive sleep apnoea in Acta Otolaryngology, 1997.117(5): p. 760-3. Or as an alternative embodiment the following stepscan be applied: spectral properties of the utterances can be analysed,resulting in a determination of the anatomical parameters of the upperairway, for instance dimensions of the throat between the vocal chordsand the mouth. In one embodiment of the invention the derived dimensionscan be used as an indicator for OSA. In other embodiments the dimensionscan be linked to other measurements for which the predictive power hasalready been established, for instance measurement data of an acousticpharyngometry measurement as illustrated in FIG. 3. FIG. 3, taken fromJung et al. shows the representative output of an acoustic pharyngometrymeasurement, having the parameter area on the Y-axis and the parameterdistance on the X-axis. One can distinguish 5 parameters on the graph(as emphasized by arrows and a thick line): (1) oropharyngeal junctionarea (OPJ), (2) Apmax, the maximum pharyngeal area, (3) glottis area(GL), (4) Apmean the mean pharyngeal area from OPJ to GL and (5) Vp, thepharyngeal volume as the integrated area under the curve between the OPJand the GL. All the parameters can be calculated by for instance theprocessing means according to embodiments of the present invention.

Alternatively, the values can also be linked to the presence of OSA in atrial that is run specifically for derivation of a detector based onspeech features. Another method to derive the cross-sectional dimensionsfrom the lips to the glottis is by applying a speech-coding by forinstance Linear Predictive Coding (LPC). LPC has can be implemented tomodel the human vocal tract. This method can also be used for obtaininga real-time estimate of the instantaneous throat geometry for optimizingrespiratory drug delivery in terms of more efficient deposition andshorter treatment times as illustrated in FIGS. 4 a and 4 b. Embodimentsof the present invention provide feedback to the patient while he/sheholds its throat open by uttering sounds, e.g. exhaling. In a subsequentinhale, while keeping the throat fixated, the drug delivery can takeplace. Direct feedback can improve adherence and compliance.

In some embodiments of the invention the determined values can becompared to predefined thresholds or used by a more sophisticatedclassifier to give a probability that the patient is suffering from OSAas illustrated in FIGS. 4 a and 4 b. The result can be given to anoperator. An example of a classifier is for instance the naïve Bayesianclassifier known in the art. The classifier can also includephysiological measures such as BMI and neck circumference to increasescreening performance. The present invention can additional be appliedfor OSA phenotyping. The throat dimensions obtained from the processingmeans can help to identify different types of OSA, providing anindication for the most successful treatment (CPAP, surgery).

An alternative embodiment of the present invention is a systemcomprising a training mode. The training mode can be applied to twogroups of patients, one group diagnosed with OSA and another groupdiagnosed non-OSA. When the two groups are examined, reference data canbe obtained which can then be used in future measurements. The processorthen autonomously can train the implemented classifier to be used forfuture tests.

In yet another embodiment the system is not only used for a one-timemeasurement but used in repeating check-ups. To this end a patient'sresults can be stored in a database (locally or remotely, notnecessarily identical with the previously mentioned database). The nexttime the patient receives a check-up the system can be used to recordanother measurement. This can then be compared to the previous resultsof this patient. This decreases the importance of absolute numbersobtained during a one-time measurement and enables the observation andevaluation of a trend. To simplify the comparison of severalmeasurements the system can be equipped with a state-of-the-artspeaker-recognition module. It autonomously can assign new measurementsto previous measurements by identifying the speaker based on theperformed utterances.

Other arrangements for accomplishing the objectives of the deviceembodying the invention will be obvious for those skilled in the art.

It is to be understood that although preferred embodiments, specificconstructions and configurations, as well as materials, have beendiscussed herein for devices according to the present invention, variouschanges or modifications in form and detail may be made withoutdeparting from the scope and spirit of this invention.

1. A system (10) for characterizing at least one anatomical parameter ofan upper airway of a patient by analysing spectral properties of anutterance, comprising: a mechanical coupler (1) comprising means forrestricting the jaw position of the patient; means (2) for recording anutterance: and processing means (5) for determining at least oneanatomical parameter of the upper airway from the recorded utterance andcomparing the recorded utterance to a threshold value.
 2. The system(10) according to claim 1 whereby said processing means (5) providesreal-time feedback (6).
 3. The system (10) according to claim 1, furthercomprising means for speech recognition for controlling correctness ofthe recorded utterance.
 4. The system (10) according to claim 1, furthercomprising means for delivering at least one respiratory drug throughsaid upper airway of the patient.
 5. The system (10) according to claim1 wherein said at least one anatomical parameter is the cross-section ofsaid upper airway and wherein said system further comprises means fordetermining at least one point of time when said cross-section ismaximal during an utterance.
 6. The system (10) according to claim 5,further comprising means for delivering at least one respiratory drugthrough said upper airway of the patient at said at least one point oftime when said cross-section of the upper airway is maximal.
 7. Thesystem (10) according to claim 4, wherein said respiratory drugdelivering means comprises a timing mechanism.
 8. Use of a systemaccording to claim 1, as a diagnostic tool for assessing obstructivesleep apnoea.
 9. A method for assessing at least one anatomicalparameter of an upper airway of a patient by analysing spectralproperties of an utterance, comprising the steps of: restricting a jawposition of the patient; recording an utterance; comparing the recordedutterance with a threshold value; and determining said at least oneanatomical parameter of the upper airway from the recorded utterance andthe comparison of the recorded utterance with a threshold value.
 10. Themethod according to claim 9, further comprising the step of providingreal-time feedback.
 11. The method according to claim 9, furthercomprising the step of adapting the patient's body position.
 12. Themethod according to claim 9, further comprising the step of storing thespectral properties of the recorded utterance in a database.
 13. Themethod according to claim 9, wherein said threshold value is determinedby means of speech recognition.
 14. The method according to claim 9,wherein said at least one anatomical parameter is the cross-section ofsaid upper airway and wherein said method further comprises the step ofdetermine at least one point of time when said cross-section is maximalwhen executing an utterance.
 15. The method according to claim 9,further comprising the step of delivering at least one respiratory drugin the upper airway of the patient.